I recently had my corrupted hard drive replaced, and while they reinstalled Windows 7 Professional for me, they didn't install some Lenovo drivers that I was used to (like a trackpad one that enabled two-finger scrolling). Since I installed the Realtek Audio driver, I haven't had sound in certain applications. The Windows startup and login sounds are fine, as is audio in Windows Media Player, but when I try to play a song in iTunes, the diamond showing the song's progress doesn't move and the play/pause/skip buttons don't work. On Youtube, videos play fine, but there's no sound. It's the same on other online streaming websites like CBS.
Occasionally, the sound will come back after startup and stay that way for up to a day, but it's never permanent. At first, I thought this had something to do with reinstalling the Realtek driver. I took my laptop to the IT guys at my college, and it seemed like they had fixed it after installing a package of Lenovo drivers, but the sound disappeared after a day or so. Two days ago, I reinstalled the Realtek driver myself and the sound came back again for a day. However, I tried doing it again today, with no luck.
Thanks so much in advance for your help!